Four deeply-nicked petals, surrounded by four greeny-red sepals, each with a pinkish-red bobble at the otherwise pointed tip. These look like hydathodes, which secrete excess water. The very long stalk has four parallel grooves where it splits to released the feathered seeds.

Of the above hybrids, and given the location of the above photographs (Llyn Idwal and Coppermines valley), there are NO Willowherbs that it could possibly be hybridized with: giving a positive identification.

The leaves have some similarities to : some Scurvygrasses. The flowers even has the same number of petals (4), but in the case of New-Zealand Willowherb, are on massively longer stalks.

No relation to : Willows [trees with similar name].

The massively long stalks upon which the tiny flowers perch become the seed pods, which, when ripe, split lengthways into four long straw-like long, thin, narrow blades, releasing the seeds which are on feathery parachutes.

A non-native from New Zealand which is spreading rapidly through the hills and indeed mountain valleys of North Wales, The Pennines, Cumbria and the Scottish hills and mountains. It is prostrate, forming matts and roots along its procumbent stems.

Two similar rock-garden escapes all the way from New Zealand (they must be tired out now having come all that way) are Rockery Willowherb (Epilobium pedunculare) and Bronzy Willowherb (Epilobium komarovianum). The two only occupy a handful of hectads in the UK, and the latter has not been seen since 1999 (according to BSBI maps).